高功率激光器输出窗口热分布数值模拟

Numerical analyses of temperature distribution of the output windows of high power lasers

利用格林函数,从一般的热传导方程出发,得到了高功率激光器输出窗口的温度场分布;针对高功率激光器中常见的环形分布激光束,计算并分析了化学氧碘激光器目前比较流行的几种光学材料蓝宝石(Al2O3 )、石英玻璃(SiO2 )、单晶硅(Si)组成的输出窗口镜的温度场分布。计算结果表明,在激光辐照的5s时间内,温升场主要集中在激光束辐照的环形区域内,在整个镜面上远未拉平。材料对激光的吸收系数及其热导率是决定温升最主要的物理参数。

According to general thermal conduction equations, the analytical expression of the temperature distributions of laser output windows subject to the irradiation of high power lasers is obtained by making use of the well-known Green′s function methods. A few kinds of optical materials such as Al_2O_3, SiO_2, and Si etc. usually used as substrates in chemical oxygen-iodine laser (COIL) systems are analyzed in detail. The temperature distributions of these substrates under irradiation of annular-distributed laser beam of high power lasers are given, discussed and compared. It is found that in 5 s of irradiation, remarkable temperature rise occurs mainly in the irradiated annular area while its distribution over the window is far from a uniform one.